Alkylation of aromatics using a metal cation-modified friedel-crafts type catalyst

ABSTRACT

A process for the alkylation of aromatic compounds with an olefin or alkyl halide having from 1 to 24 carbon atoms utilizes a novel catalyst comprising: a) a refractory inorganic oxide, b) the reaction product of a first metal halide and bound surface hydroxyl groups of the refractory inorganic oxide, c) a second metal cation, and d) optionally a zerovalent third metal. The refractory inorganic oxide is selected from the group consisting of alumina, titania, zirconia, chromia, silica, boria, silica-alumina, and combinations thereof and the first metal halide is a fluoride, chloride, or bromide of aluminum, gallium, zirconium, or boron. The second metal cation is selected from the group consisting of: monovalent metal cations in an amount from 0.0026 up to about 0.20 gram atoms per 100 grams refractory inorganic oxide for lithium, potassium, cerium, rubidium, silver, and copper, and from 0.012 to about 0.20 gram atoms for sodium; and alkaline earth metal cations in an amount from about 0.0013 up to about 0.01 gram atoms per 100 grams of refractory inorganic oxide for beryllium, strontium, and barium, and in an amount from about 0.004 up to about 0.1 gram atoms per 100 grams support for magnesium and calcium, or combinations thereof. The third metal is selected from the group consisting of platinum, palladium, nickel ruthenium, rhodium, osmium and iridium, and any combination thereof. These novel catalysts are effective in other alkylation reactions including motor fuel alkylation.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of my application Ser. No.08/533,576 now U.S. Pat. No. 5,672,797, filed Sep. 25, 1995, which is acontinuation-in-part of Ser. No. 08/265,161, filed Jun. 24, 1994, nowabandoned, which is a continuation-in-part of Ser. No. 08/093,150, filedJul. 19, 1993, now abandoned, all of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

Over fifty years ago it was recognized that alkylbenzene sulfonates(ABS) were quite effective detergents superior to natural soaps in manyrespects. Because of their lower price, their price stability, and theireffectiveness in a wide range of detergent formulations, ABS rapidlydisplaced soaps in household laundry and dishwashing applications andbecame the standard surfactants for the detergent industry.

The alkylbenzene sulfonates as initially prepared had substantialbranching in the alkyl chain. This situation was maintained until theearly 1960's when it became apparent that the branched alkyl-baseddetergents were contributing to the pollution of lakes and streams andforming relatively stable foams. Examination of the problem showed thatthe branched structure of the alkyl chains was not susceptible to rapidbiodegradation and the surfactant properties of the detergent thuspersisted for long periods of time. This was not the case earlier whennatural soaps were used because of the rapid biodegradation of thelinear chains in natural soaps.

After recognizing the biodegradability of ABS based on alkylation bylinear olefins, industry turned its attention to the production of theseunbranched olefins and their subsequent use in the production of linearalkyl benzenes. Processes were developed for efficient alkylation ofbenzene by available feedstocks containing linear olefins, and theproduction of linear alkyl benzenes (LAB) became another reliableprocess broadly available to the petroleum and petrochemical industry.It gradually evolved that HF-catalyzed alkylation was particularlyeffective in LAB production, and an HF-based alkylation process becamethe industry standard.

With increasing environmental concern came increasing disenchantmentwith HF as a catalyst and a concomitant need to find a substitute equalor superior to it in all respects. As regards criteria in addition tothe price, the extent of conversion effected by the catalyst, theselectivity of monoalkylbenzene formation, and the linearity ofalkylbenzenes produced loomed large. At this point the definition ofseveral terms are necessary to adequately understand and appreciate whatfollows.

Alkylation typically is performed using an excess of benzene relative toolefins. The ideal catalyst would show 100% conversion of olefins usingan equal molar proportion of benzene and olefins, but since this has notbeen attainable one strives for maximum olefin conversion using abenzene to olefin molar ratio up to about 30. The better the catalyst,the lower will be the benzene:olefin ratio at a high conversion of, say,98%. The degree of conversion at a constant value of benzene-olefinratio is a measure of catalytic activity (subject to the caveat that theratio must not be so high that the degree of conversion is invariant tosmall changes in this ratio). The degree of conversion may be expressedby the formula, ##EQU1## where V equals percent conversion, C equalsmoles of olefin consumed, and T equals moles olefin initially present.

However active the catalyst may be, it is not valuable unless it also isselective. Selectivity is defined as the percentage of total olefinconsumed under reaction conditions which appears as monoalkylbenzene andcan be expressed by the equation, ##EQU2## where S equals selectivity, Mequals moles of monoalkylbenzenes produced, and C equals moles olefinconsumed. The better the selectivity, the more desirable is thecatalyst. An approximate measure of selectivity is given by theequation, ##EQU3## where "total products" includes monoalkylbenzenes,polyalkylbenzenes, and olefin oligomers. At high selectivity (S>85%) theresults calculated from the two equations are nearly identical. Thelatter of the foregoing two equations is routinely used in commercialpractice because of the difficulty in distinguishing between oligomersand polyalkylbenzenes.

Finally, the reaction of linear olefins with benzene in principalproceeds according to the equation,

    C.sub.6 H.sub.6 +R.sub.1 CH═CHR.sub.2-- >C.sub.6 H.sub.5 CH(R.sub.1)CH.sub.2 R.sub.2 +C.sub.6 H.sub.5 CH(R.sub.2)CH.sub.2 R.sub.1.

Note that the side chain is branched solely at the benzylic carbon andcontains only one branch in the chain. Although strictly speaking thisis not a linear alkylbenzene, nonetheless the terminology which hasgrown up around the process and product in fact includes as linearalkylbenzenes those materials whose alkyl group chemically arisesdirectly from linear olefins and therefore includes alpha-branchedolefins. Because alkylation catalysts also may induce the rearrangementof olefins to give products which are not readily biodegradable (videsupra), for example, α,α-disubstituted olefins which subsequently reactwith benzene to afford an alkyl benzene with branching at other than thebenzylic carbon, ##STR1## the degree to which the catalyst effectsformation of linear alkyl benzenes is another important catalystparameter. The degree of linearity can be expressed by the equation,##EQU4## where D equals degree of linearity, L equals moles of linearmonoalkyl benzene produced, and M equals moles of monoalkyl benzeneproduced.

Consequently, the ideal catalyst is one where V equals 100, S equals100, and D equals 100. The minimum requirement is that linearity be atleast 90% at a selectivity of at least 85% and at a conversion of atleast 98%. These are minimum requirements; that is, if a catalyst failsto meet all of the foregoing requirements simultaneously the catalyst iscommercially unacceptable.

The linearity requirement is assuming added importance and significancein view of the expectation in some areas of minimum standards forlinearity in detergents of 92-95% near-term, increasing to 95-98% byabout the year 2000. Since the olefinic feedstock used for alkylationgenerally contains a small percentage of non-linear olefins--a non-linerolefin content of about 2% is common to many processes--the requisitelinearity in the detergent alkylate places even more stringentrequirements on catalytic performance; the inherent linearity of thealkylation process must increase by the amount of non-linear olefinspresent in the feedstock. For example, with a feedstock containing 2%non-linear olefins the catalyst must effect alkylation with 92%linearity in order to afford a product with 90% linearity, and with afeedstock containing 4% non-linear olefins the catalyst must effectalkylation with 94% linearity to achieve the same result.

Our solution to the problem of identifying a catalyst for detergentalkylation which satisfies all the aforementioned criteria, and which inparticular meets the increasingly stringent requirements of linearity,arose from our observation that the isomerization of linear olefins tonon-linear olefins--this is the process ultimately responsible fornon-linear detergent alkylate arising from a linear olefin feedstock--isquite sensitive to temperature but relatively insensitive to theparticular candidate catalyst for the detergent alkylate process. Thisresult was itself quite surprising, but more importantly it suggestedthat effecting alkylation at a lower temperature was the key to greaterproduct linearity. Our focus then shifted to finding more activecatalysts, i.e., materials which would catalyze detergent alkylation atlower temperatures.

The importance of our observation that temperature is the major factorin olefin isomerization and that the particular catalyst plays only aminor role cannot be overemphasized, for it permits one to focus solelyon methods of reducing the alkylation temperature. Since the otherrequisites of a detergent alkylation process can be addressed in otherways, our observation significantly foreshortens the focus on ways toobtain an improved process. A result of our observation is the novel useof a solid acid catalyst to craft a new process permitting alkylation ata substantially lower temperature than that previously attainable usingother members of this class of catalysts.

SUMMARY OF THE INVENTION

The object of this invention is to prepare linear alkylbenzenes by thealkylation of benzene with an olefin, particularly in a continuousmanner, where alkylation proceeds with at least 90% selectivity ofolefin conversion to monoalkylbenzenes, and with at least 90% linearitywith respect to monoalkylbenzene formation. In an embodiment benzene ina total of from 5 to about 30 molar proportions is reacted with 1 molarproportion of a linear monoolefin, or a mixture of linear monoolefins,in the presence of a catalyst which is a composite of a Friedel-Craftstype metal halide bound to the surface hydroxyl groups of refractoryinorganic oxide, a zerovalent metal having hydrogenation activity, andanother metal cation. In a more specific embodiment the linearmonoolefins have from 6 up to about 20 carbon atoms. In a still morespecific embodiment the molar proportion of total benzene relative tototal linear monoolefins is from about 8:1 to about 20:1. Otherembodiments will be apparent from the ensuing description.

A broader object of this invention is a process for the liquid phasealkylation of aromatic compounds with a variety of alkylating agentsusing as a catalyst the aforementioned composite. In a specificembodiment of this branch of our invention the alkylating agent is anolefin containing up to about 24 carbon atoms. In another embodiment thealkylating agent is an alcohol containing from 1 up to about 24 carbonatoms.

DESCRIPTION OF THE INVENTION

In our search for catalysts in a detergent alkylation process, andespecially solid catalysts capable of being used as a bed in acontinuous fixed bed detergent alkylation process, it soon became clearthat the degree of branching in the alkyl chain of the resultingalkylbenzene (detergent alkylate) was principally a function oftemperature, with lower reaction temperatures affording lower branching.Since linearity of the alkyl chain is an increasingly importantenvironmental and regulatory consideration, our observation led to asearch for catalysts which would effect alkylation in a continuousprocess at acceptable productivity rates and at a temperature notexceeding 140° C. For the purpose of this application an acceptableproductivity means an olefin liquid hourly space velocity of at least0.05 hr⁻¹. What we have found is that certain modified Friedel-Craftstype catalysts, where the metal halide is reacted with the surfacehydroxyl groups of refractory organic oxides, having coimpregnatedzerovalent metals with hydrogenation activity and monovalent or divalentmetal cations, principally of the alkali metal or alkaline earth metalseries, are quite suitable catalysts for a detergent alkylation processat temperatures not exceeding 140° C. and effect detergent alkylationwith at least 90% selectivity to monoalkylbenzenes and with at least 90%linearity of the alkyl side chain. Although our invention isparticularly relevant to detergent alkylation, it is important tounderstand that our invention is generally applicable to the alkylationof alkylatable aromatic compounds with a large universe of alkylatingagents, as will be clear from the material within.

The feedstocks containing the alkylating agent which are used in thepractice of that branch of our invention applicable to detergentalkylation normally result from the dehydrogenation of paraffins. Sincethe entire dehydrogenation reaction mixture often is used, the reactionis not run to completion to minimize cracking, isomerization, and otherundesirable and deleterious byproducts. The branched olefins which areformed are not removed, yet the total amount of nonlinear alkylbenzeneformed still must be sufficiently small that the monoalkylate meets therequirements of 90% linearity. The polyolefins formed duringdehydrogenation are minimized in the feedstocks used in the practice ofthis invention. Consequently the feedstocks are largely a mixture ofunreacted paraffins and unbranched, linear monoolefins which typicallyare in the C6-C20 range, although those in the C8-C16 range arepreferred in the practice of this invention, and those in the C10-C14range are even more preferred. Unsaturation may appear anywhere on thelinear monoolefin chain; there is no requirement as to the position ofthe double bond, but only a requirement as to the linearity of theolefin. See R. A. Myers, "Petroleum Refining Processes", 4-36 to 4-38.(McGraw-Hill Book Company), 1986.

In the broader case the alkylating agent is an olefin, an alcohol, or analkyl halide containing from 1 up to about 24 carbon atoms. Where thealkylating agent is an olefin the latter may be either branched orunbranched and also may be substituted with, for example, an aromaticsubstituent. Examples of suitable olefins include ethylene, propylene,the butenes, pentenes, hexenes, heptenes, octenes, nonenes, decenes,undecenes, dodecenes, tridecenes, tetradecenes, pentadecenes,hexadecenes, heptadecenes, octadecenes, nonadecenes, eicosenes,heneicosenes, docosenes, tricosenes, and tetracosenes. Further examplesinclude styrene, phenylpropene, phenylbutene, phenylpentene,phenylhexene, and so forth.

Another class of alkylating agents which may be used in the practice ofour invention are alcohols. Like the olefins, the alkyl chain in thealcohol may be branched or unbranched and the hydroxyl group may befound anywhere on the alkyl chain. That is, there is no particularrequirement as to the spatial position of the hydroxyl moiety on thealkene chain. Examples of alcohols which may be successfully used in ourinvention include methanol, ethanol, propanol, butanol, pentanol,hexanol, heptanol, octanol, nonanol, decanol, undecanol, tetradecanol,and so forth. Especially relevant to this branch of the invention ismethanol as the alcohol.

The last of the three classes of alkylating agents which may befrequently used in the practice of this invention are alkyl halides.Alkyl chlorides are probably the most widely used alkyl halides, butalkyl bromides also may be successfully used in the practice of ourinvention. As with alcohols, the paraffinic chain may be either branchedor unbranched and the halogen may be found at any position along thechain. Suitable examples of alkyl halides include propyl chloride,propyl bromide, butyl chloride, butyl bromide, pentyl chloride, pentylbromide, hexyl chloride, hexyl bromide, heptyl chloride, heptyl bromide,benzyl chloride, benzyl bromide, xylyl chloride, xylyl bromide,phenethyl chloride, phenethyl bromide, allyl chloride, allyl bromide,butenyl chloride, butenyl bromide, and so forth.

Where the process is detergent alkylation, the linear monoolefins in thefeedstock are reacted with benzene. Although the stoichiometry of thealkylation reaction requires only 1 molar proportion of benzene per moleof total linear monoolefins, the use of a 1:1 mole proportion results inexcessive olefin polymerization and polyalkylation. That is, thereaction product under such conditions would consist of not only thedesired monoalkylbenzenes, but would also contain large amounts of thedialkylbenzenes, trialkylbenzenes, possibly higher polyalkylatedbenzenes, olefin dimers, trimers, etc., and unreacted benzene. On theother hand, it is desired to have the benzene:olefin molar ratio asclose to 1:1 as possible to maximize benzene utilization and to minimizethe recycle of unreacted benzene. The actual molar proportion of benzeneto total monoolefins will therefore have an important effect on bothconversion and, perhaps more importantly, selectivity of the alkylationreaction. In order to carry out alkylation with the conversion,selectivity, and linearity required using the catalysts of our process,a total benzene:linear monoolefin molar ratio of from 5:1 up to as highas 30:1 is recommended, although the process normally operatessatisfactorily at a total benzene:linear monoolefins molar ratio betweenabout 8:1 and about 20:1.

In the more general case the alkylating agent is reacted with analkylatable aromatic compound. Such aromatic compounds are selected fromthe group consisting of benzene, naphthalene, anthracene,phenanthracene, and substituted derivatives thereof. The most importantclass of substituents are alkyl moieties containing from 1 up to about20 carbon atoms. Another important substituent is the hydroxyl moiety aswell as the alkoxy moiety whose alkyl group also contains from 1 up to20 carbon atoms. Where the substituent is an alkyl or alkoxy group, aphenyl moiety also can be substituted on the paraffinic chain. Althoughunsubstituted and monosubstituted benzenes, naphthalenes, anthracenes,and phenanthrenes are most often used in the practice of this invention,polysubstituted aromatics also may be employed. Examples of suitablealkylatable aromatic compounds include benzene, naphthalene, anthracene,phenanthrene, biphenyl, toluene, xylene, ethylbenzene, phenol, anisole,propylbenzene, butylbenzene, pentylbenzene, hexylbenzene, heptylbenzene,octylbenzene, and so forth; anisole, ethoxy-, propoxy-, butoxy-,pentoxy-, hexoxybenzene, and so forth.

Where the process is detergent alkylation, the benzene and linearmonoolefins in the C₆ -C₂₀ range, are reacted in the presence of acatalyst under alkylation conditions. These alkylation conditionsinclude a temperature in the range between about 60° C. and 140° C., andpreferably in the range from 70 to 135° C. Since the alkylation isconducted as a liquid phase process, pressures must be sufficient tomaintain the reactants in the liquid state. The requisite pressurenecessarily depends upon the feedstock and temperature, but normally isin the range of 200-1000 psig (1379-6985 kPa), and most usually 300-500psig (2069-3448 kPa).

In the more general case, there is a wide variation in the alkylationconditions of an alkylatable aromatic compound by an alkylating agentdepending upon the reactivity of the two reactants. For example, forhydroxy benzenes (phenols) the hydroxyl moiety is found to be a quiteactivating group toward alkylation, and therefore the hydroxy benzenesare readily alkylated so that temperatures of no more than about 150° C.suffice. On the other hand, where the aromatic is an unsubstitutedaromatic, such as benzene, and the alkylating agent is a lower olefin,such as propylene, temperatures as high as 400° C. may be necessary.Consequently, the temperature range appropriate for alkylation will bebetween about 60 and about 400° C., with the most usual temperaturerange being between 100 and 225° C. As regards pressures, since thealkylation is desirably conducted as a liquid phase process the reactionpressure must be sufficient to maintain the reactants in the liquidstage. This is the sole pressure requirement for the practice of thisinvention, and since a wide variety of alkylatable aromatics compoundsand alkylating agents may be used in the practice of this invention itcan be readily appreciated that there exists a wide variation inreaction pressure, from atmospheric up to as high as about 2000 poundsper square inch (14,000 kPa).

The alkylation of benzene by linear monoolefins with the requisiteconversion, selectivity, and linearity is effected by the catalysts ofour invention which can be referred to as metal cation-modifiedFriedel-Crafts type metal halides supported on refractory inorganicoxides via reaction of their surface hydroxyl groups with the metalhalide, where the refractory inorganic oxide also is optionallycoimpregnated with at least one metal having hydrogenation activity. Theanalogs of our catalyst without the metal cations of our invention arewell known in the art (see U.S. Pat. Nos. 2,999,074; cf. 3,318,820) andthe extensive descriptions of their preparations are applicable to ourcatalyst with the exception of impregnation with a monovalent cation oralkaline earth metal cation. Thus, much of the prior art description isapplicable to our catalysts and makes a detailed description of theirpreparation unnecessary. The following description then will sufficemerely to afford the reader an understanding of our invention.

The refractory inorganic oxides suitable for use in this invention havea surface area of at least about 35 m² /g, preferably greater than about50 m² /g, and more desirably greater than 100 m² /g. There appears to besome advantage to working with materials having as high a surface areaas possible, although exceptions are known which preclude making this ageneral statement. Suitable refractory inorganic oxides include alumina,titania, zirconia, chromia, silica, boria, silica-alumina, andcombinations thereof. Of these alumina is particularly preferred. Anyalumina phase may be used so long as it has a surface area of at least35 m² /g and has surface hydroxyl groups, which for all practicalmatters excludes alpha-alumina. Among the phases which may be used areincluded gamma-, etc-, and theta-alumina, although the various phasesare not necessarily equivalent in their effectiveness as an alkylationcatalyst. Aluminum phosphate is another favored refractory material.

It is required that the refractory inorganic oxide have bound surfacehydroxyl groups, by which is meant not adsorbed water but ratherhydroxyl (OH) groups whose oxygen is bound to the metal of the inorganicoxide. These latter hydroxyl groups sometimes have been referred to aschemically combined hydroxyl. Since the presence of adsorbed water isgenerally detrimental to the preparation of the catalysts of ourinvention, the refractory inorganic oxides are first treated to removesurface hydroxyl groups arising from water, most usually by calcinationat a temperature which specifically and preferentially removesphysically adsorbed water without chemically altering the other hydroxylgroups. For example, calcination temperatures ranging from about 350° C.to about 700° C. are usually satisfactory where the inorganic oxide isalumina.

The catalytic composites of our invention optionally contain a metalhaving hydrogenation activity. Although the presence of this componentis not necessary for alkylation activity, we have found its presence maybe desirable in subsequent catalyst regeneration. Where ahydrogenation-active metal is present it generally is deposited on therefractory inorganic oxide prior to the reaction of its bound surfacehydroxyl groups with metal halides. Although such a procedure has provenboth convenient and effective, we do not wish to imply that this is theonly sequence which may be used to afford an effective catalyst. Metalswhich have been found to be particularly effective include nickel andthe noble metals of platinum, palladium, ruthenium, rhodium, osmium, andiridium, although platinum and palladium are by far the most desirableof the noble metals. The desired metal may be composited with therefractory inorganic oxide in any desired manner, such as byimpregnation, coprecipitation, dipping, and so forth, of a suitable saltfollowed by reduction of the metal to its zerovalent state. Such methodsare well known and need not be described here. Hydrogenation-activemetal levels may range between about 0.01 up to about 1.0 weight percentfor the noble metals, based on the weight of the finished catalyst, andfrom about 0.1 up to about 5 weight percent for nickel. The composite ofthe metal and refractory inorganic oxide is dried and calcined undercontrolled conditions to remove physically adsorbed water but undersufficiently mild conditions so that the "chemically combined" hydroxylgroups are not eliminated.

The more usual way of introducing a hydrogenation-active metal into thecatalytic composites of our invention is by coimpregnation of therefractory inorganic oxide with a salt of the hydrogenation-active metaltogether with one or more monovalent or alkaline earth metal cations ofour invention. But as stated above it is not believed that theparticular procedure or sequence used is determinative of success of, oreven of substantial significance to, the final catalytic composite.

The next stage in the preparation of our catalytic composites, whetheror not a metal with hydrogenation activity has been deposited thereon,is to deposit on the composite one or more monovalent metal or alkalineearth metal cations. Such metals include lithium, sodium, potassium,cesium, rubidium, silver, copper(I), beryllium, magnesium, calcium,strontium, and barium. Among the monovalent metal cations the alkalimetal cations are favored. The amount of metal cation which isimpregnated on the composite is in most cases an amount having a gramatom equivalent from about 0.1 up to about 8 weight percent potassium,which is 0.0026 gram atoms potassium up to 0.2 gram atoms per 100 gramsupport. We define a "gram atom equivalent" of another metal cation asbeing a number of gram atoms of the metal divided by its valence per 100grams support. For example, for most divalent atoms the gram atomequivalent is 0.0013 up to about 0.1 gram atoms per 100 gram support.

There is some irregularity in the amount of metal cations which are tobe impregnated upon the refractory inorganic oxides which are thesupports in our invention. For the monovalent cations of lithium,potassium, cesium, rubidium, silver and copper, the amounts depositedare from 0.0026 to about 0.20 gram atom per 100 grams support; forsodium the amount is from 0.009 to about 0.20 gram atom per 100 gramssupport. For the divalent cations beryllium, strontium, and barium theamount is from 0.0013 to about 0.1 gram atoms per 100 gram support; formagnesium and calcium the amount is from 0.004 to about 0.1 gram atomsper 100 gram support. These amounts in terms of grams of metal cationper 100 gram support are summarized in the following table. Since thepreferred range is from 0.012 up to about 0.12 gram atoms for monovalentcations, and 0.006 up to about 0.06 gram atoms for divalent metalcations, the preferred ranges also are listed in the following table. Itneeds to be emphasized that in all cases the minimum amount of cationadded is well outside that normally found as impurities in the supportsof our invention, hence will not be present incidental to theirpreparation.

                  TABLE    ______________________________________    Amounts of Metal Cations on Supports    (grams per 100 gram support)           Range         Preferred Range    Metal Cation             Minimum   Maximum   Minimum Maximum    ______________________________________    Monovalent    Lithium  0.02      1.4       0.1     0.8    Sodium   0.2       4.6       0.3     2.8    Potassium             0.1       7.8       0.5     4.7    Cesium   0.3       26.6      1.6     15.9    Rubidium 0.2       17.1      1.0     10.3    Copper(I)             0.2       12.7      0.8     7.6    Silver   0.3       21.6      1.3     12.9    Divalent    Beryllium             0.01      0.9       0.1     0.5    Magnesium             0.1       2.4       0.1     1.5    Calcium  0.2       4.0       0.2     2.4    Strontium             0.1       8.8       0.5     5.3    Barium   0.2       13.7      0.8     8.2    ______________________________________

Impregnation of the composite by the monovalent metal or alkaline earthmetal cation may be done simply by mixing the composite with a suitableaqueous solution of the salt and removing water. The particularmonovalent or alkaline earth metal salt used is not especially importantso long as it provides sufficient solubility in water. As a practicalmatter, the halides, nitrates, and acetates may be the most commonlyemployed salts. Salts prone to precipitation should be avoided in orderto avoid non-uniform impregnation, but otherwise there are no seriouslimitations on the salts which may be used. After evaporation of excesswater, materials generally are dried at a temperature between about 100and 200° C. for 24 hours and then calcined at a temperature whichspecifically and preferentially removes physically adsorbed waterwithout chemically altering the other hydroxyl groups. As mentionedbefore, temperatures ranging from about 350° C. to about 700° C. usuallyare satisfactory where the inorganic oxide is alumina.

Subsequent to metal deposition and calcination, the bound surfacehydroxyl groups of the refractory inorganic oxide are reacted with ametal halide having Friedel-Crafts activity. Among the metals which maybe used are included aluminum, zirconium, tin, tantalum, titanium,gallium, antimony, and boron. Suitable halides are the fluorides,chlorides, and bromides. Representative of such metal halides includealuminum chloride, aluminum bromide, ferric chloride, ferric bromide,zirconium chloride, zirconium bromide, boron trifluoride, titaniumtetrachloride, gallium chloride, tin tetrachloride, antimony fluoride,tantalum chloride, tantalum fluoride, and so forth. Of these metalhalides the aluminum halides are preferred, especially aluminumchloride. Except for boron trifluoride, the chlorides are generally thepreferable halides.

The reaction between the metal halides of this invention and the boundsurface hydroxyl groups of the refractory inorganic oxide is readilyaccomplished by, for example, sublimation or distillation of the metalhalide onto the surface of the particles of the metal inorganic oxidecomposite. The reaction is attended by the elimination of between about0.5 and 2.0 moles of hydrogen halide per mole of metal halide adsorbedthereon. The reaction temperature will depend upon such variables as thereactivity of the metal halides and its sublimation temperature orboiling point, where the metal halide is reacted in the gas phase, aswell as on the nature of the refractory inorganic oxide. For example,using aluminum chloride and alumina as our specific examples reactionreadily occurs within the range between about 190 through 600° C.

The amount of metal halide which is reacted with the bound surfacehydroxyl groups of the refractory inorganic oxide is generally given interms of the weight percent of the Friedel-Crafts metal on thecomposite. This amount will vary with the refractory inorganic oxideused, the relative number of bound surface hydroxyls of the inorganicoxide (which may be related to the particular oxide phase utilized), thespecific Friedel-Crafts metal halide employed, as well as the particularprocedure used to effect reaction between the Friedel-Crafts type metalhalide and the bound surface hydroxyl. As a rough rule of thumb foraluminum chloride on alumina, as an example, the amount of aluminumchloride reacted expressed as weight percent aluminum in the finalcomposite ranges from about 0.1 up to about 2.5%, with the level being afunction primarily of the number of bound surface hydroxyl groups on therefractory inorganic oxide.

It has been found that the catalysts of my invention are quite sensitiveto water. Thus it is desirable that the feedstocks be dried to a levelof 1 ppm or less, most preferably to a level of not more than 0.1 ppmwater. With increasing feedstock water content the catalysts are foundto deactivate. It also is quite desirable to dry the catalyst thoroughlyimmediately prior to use. This can be successfully done by heating mycatalysts in a dry, unreactive gas such as air or nitrogen at atemperature of at least 150° C., but preferably at even highertemperatures. The time needed for adequate drying will depend on suchfactors as gas flow rate and temperature, but at 300° C. a time from 6to about 12 hours appears adequate. The catalytic composites of myinvention also are quite sensitive to other materials as well, such asorganic nitrogen compounds, organic oxygenates, and sulfur compoundsgenerally. Thus, it is preferable to use feedstocks containing less than0.1 ppm nitrogen, less than 0.2 ppm oxygenates, and less than 10 ppmsulfur.

Alkylation of benzene by the detergent-range linear monoolefins of thisinvention may be conducted either as a batch method or in a continuousmanner, although the latter is greatly preferred and therefore will bedescribed in some detail. The composites of this invention used ascatalyst may be used as a packed bed or a fluidized bed. Feedstock tothe reaction zone may be passed either upflow or downflow, or evenhorizontally as in a radial bed reactor. The admixture of benzene andthe feedstock containing the total linear monoolefins is introduced at atotal benzene:olefin ratio of between 5:1 and 30:1, although usually theratio is in the range between about 8:1 and 20:1. In one desirablevariant olefin may be fed into several discrete points within thereaction zone, and at each zone the benzene:olefin ratio may be greaterthan 30:1. However, the total benzene:olefin ratio used in the foregoingvariant of my invention still will be within the stated range. The totalfeed mixture, that is, benzene plus feedstock containing linearmonoolefins, is passed through the packed bed at a liquid hourly spacevelocity (LHSV) between about 0.3 and about 6 hr⁻¹ depending uponalkylation temperature, how long the catalyst has been used, the ratioof silica to alumina and fluoride level in the catalyst, and so on. Thetemperature in the reaction zone will be maintained at between about 60and about 140° C., and pressures generally will vary between about 200and about 1000 psig (1379-6895 kPa) to ensure a liquid phase alkylation.After passage of the benzene and linear monoolefin feedstock through thereaction zone, the effluent is collected and separated into benzene,which is recycled to the feed end of the reaction zone, paraffin, whichis recycled to the dehydrogenation unit, and alkylated benzenes. Thealkylated benzenes are usually further separated into the monoalkylbenzenes, used in subsequent sulfonation to prepare the linearalkylbenzene sulfonates, and the oligomers plus polyalkylbenzenes. Sincethe reaction usually goes to at least 98% conversion, little unreactedmonoolefin is recycled with paraffin.

For alkylation other than detergent alkylation, i.e., in the moregeneral case, the reaction between the alkylatable aromatic compound andthe alkylating agent will also be performed generally as describedabove. Whether the aromatic or the alkylating agent is used in excessdepends upon the relative economics of the process, the desirability ofthe predominance of a particular product, the tendency towardoligomerization of, for example, the olefin, and so forth. However, ingeneral the ratio of the alkylatable aromatic substrate and alkylatingagent may range between about 1:20 and 20:1. As stated previously,alkylation temperatures will be in the range of 60-400° C., althoughtemperatures between 100 and 225° C. are more the norm. Pressures willbe adequate to ensure a liquid phase alkylation and usually will be nomore than about 500 pounds per square inch, although in the case oflower olefins higher temperatures up to perhaps 2,000 psig may beemployed. Whether there is recycling of any of the unreacted componentswill depend, inter alia, upon the extent of conversion, the economicvalue of the reactant, the ease with which the unreacted materials areseparated from the reaction products, and so forth.

For either type of alkylation we have observed that the presence ofchloride at low levels is necessary to initiate alkylation. Among thechlorides which may be used in the practice of this invention areincluded alkyl chlorides, which under reaction conditions undergodehydrohalogenation with formation of HCl. Hydrogen chloride itself alsomay be used directly, instead of generating it from an alkyl chloride.It is common to use an alkyl chloride which may be of the same carbonnumber as the alkylation agent (i.e., olefin). Examples of alkylchloride commonly used include butyl chloride, pentyl chloride, hexylchloride, octyl chloride, nonyl chloride, decyl chloride, and so on.Since secondary alkyl chlorides dehydrohalogenate more readily than doprimary alkyl chlorides they are somewhat favored over the latter. Ofcourse, tertiary alkyl chlorides also may be used in the practice ofthis invention. Whatever halide is the source of HCl, it is present inan amount sufficient to afford from about 5 up to about 5000 ppmchloride, preferably from 50 to about 500 ppm chloride. Hydrogenchloride per se may be used directly at the foregoing concentrations.

The following examples are illustrative only. They show in some detailhow the invention claimed below may be carried out but are not intendedto limit the invention in any way.

EXAMPLE 1

General Procedure. Catalyst was packed in a bed 0.5 inch in diameter and8 inches long equipped with a sliding thermocouple to survey bedtemperature at various depths. The feedstock containing linearmonoolefins resulted from dehydrogenation of n-paraffins and had thecomposition given below.

                  TABLE 1    ______________________________________    Feedstock Composition (weight percent)    Branched hydrocarbons                        7.9    Unbranched hydrocarbons                       92.1                 Alkenes                       Alkanes    ______________________________________    C9             <0.1    0.1    C10            0.9     7.9    C11            4.1     31.8    C12            3.6     24.8    C13            2.6     15.7    C14            0.1     0.4    Total          11.3    80.7    ______________________________________

The feedstock containing the linear monoolefins and benzene at a molarratio of 10:1 benzene:olefin was fed upflow to the packed bed ofcatalyst at conditions given in the table. Effluent was analyzed by gaschromatography. Analyses were performed after the reactor had lined out,that is, after equilibrium had been attained.

Alkylation with catalytic composites. AlCl₃ supported on 1 wt. % Kmodified gamma alumina was tested for the alkylation of benzene withnormal decene. This test was conducted in the presence of a small amountof n-octylchloride (the 1-chloro isomer). At 60° C. and about 80% deceneconversion, about 97% linear decylbenzene was produced. Selectivity tomonoalkylbenzene was about 90% at this condition (feedbenzene/olefin=10). Conversion was increased to 97% by raising thetemperature to 120° C. where linearity was about 93% and selectivityincreased to about 94%. Higher conversion at lower temperature should beachievable by using a secondary Cl isomer.

EXAMPLE 2

Trace Metal Analyses of Aluminas. Alumina samples used as catalystsupports were routinely analyzed for trace metals. Typical results forthree representative aluminas indicated as samples A-C, are given below;the sample identified as "Kaiser" is a commercial alumina from KaiserAlumina sold under the name Versal-250.

                  TABLE 4    ______________________________________    Trace Metals in Alumina    Metal (in ppm)              Sample A  Sample B  Sample C                                          Kaiser    ______________________________________    Na        98        20        23      <1000    Mg        <10       30        <10     <100    Ca        <300      <300      <300    <300    Cu        <10       <10               <10    ______________________________________

Two types of commercial aluminas as well as an alumina routinelyprepared for applicants were analyzed for trace metals by GalbraithLaboratories, an independent and well known analytical laboratory.Results obtained by them are found in Table 5. Catapal is a commercialalumina made by Vista. Versal-250 is a commercial alumina made by KaiserAlumina; this sample is different from the one above. Sample D is analumina routinely prepared by applicants' assignee.

                  TABLE 5    ______________________________________    Trace Analyses by Independent Laboratory    Metal (in ppm)               Catapal    Versal-250                                    Sample D    ______________________________________    Na         1400       1850      1720    K          380        380       400    Ca         <35        85        114    Mg         <35        <34       <26    ______________________________________

The foregoing data show the maximum amounts (in ppm) of trace metals invarious types of commercial alumina is:

Na<2000 ppm

K≦400 ppm

Ca<300 ppm

Mg<35 ppm

Cu<10 ppm

These maximum levels are representative of those found in aluminas fromvarious sources and demonstrate that the amounts added by applicants arefar in excess of what may be reasonably expected to occur in merchantalumina.

What is claimed is:
 1. In the method for alkylating benzene with one ormore linear monoolefins with at least 90% selectivity of olefinconversion to monoalkylbenzenes, and with at least 90% linearity withrespect to monoalkylbenzene formation comprising reacting benzene withthe linear monoolefins in a feedstock at alkylating conditions and inthe presence of a catalyst, said feedstock containing at least onelinear monoolefin, said alkylating conditions including reacting fromabout 5 to about 30 molar proportions of total benzene for each molarproportion of total linear monoolefins at a temperature from about 60°C. to about 140° C. and a pressure from about 200 to about 1000 psig,where the catalyst comprises a) a refractory inorganic oxide, b) thereaction product of a first metal halide and bound surface hydroxylgroups of said refractory inorganic oxide, c) a second metal cation, andd) optionally a zerovalent third metal; where said refractory inorganicoxide is selected from the group consisting of alumina, titania,zirconia, chromia, silica, boria, silica-alumina, and combinationsthereof; said first metal halide is a fluoride, chloride, or bromide ofaluminum; said second metal cation is selected from the group consistingof a) monovalent metal cations in an amount from 0.0026 up to about 0.20gram atoms per 100 grams refractory inorganic oxide for lithium,potassium, cerium, rubidium, silver, and copper, and in an amount from0.012 to about 0.12 gram atoms for sodium, and b) alkaline earth metalcations in an amount from about 0.0013 up to about 0.01 gram atoms per100 grams of refractory inorganic oxide for beryllium, strontium, andbarium, and an amount from about 0.004 up to about 0.1 gram atoms per100 grams support for magnesium and calcium, and any combinationthereof; and said third metal is selected from the group consisting ofplatinum, palladium, nickel, ruthenium, rhodium, osmium and iridium, andany combination thereof; the improvement comprising using a feedstockcontaining less than 0.1 ppm nitrogen, less than 0.2 ppm oxygenates,less than 0.1 ppm water, and less than 10 ppm sulfur.
 2. The method ofclaim 1 where the molar ratio of benzene to linear monoolefins is fromabout 8 to about
 20. 3. The method of claim 1 where the temperature doesnot exceed 135° C.
 4. The method of claim 1 where the monoolefins havefrom about 6 to about 20 carbon atoms.
 5. The method of claim 4 wherethe monolefins have from about 8 to about 16 carbon atoms.
 6. The methodof claim 5 where the monoolefins have from about 10 to about 14 carbonatoms.
 7. The process of claim 1 where alkylating conditions include atemperature from about 60 up to about 400° C. and a cofeed of HCl or analkyl chloride at concentrations effective to afford from 5 up to about5000 ppm chloride.
 8. The process of claim 1 where the refractoryinorganic oxide is alumina.
 9. The process of claim 8 where the aluminais a gamma, theta, or eta alumina.
 10. The catalytic composite of claim1 where the second metal cation is selected from the group consisting oflithium, sodium, potassium, cesium, rubidium, silver, copper(I),beryllium, magnesium, calcium, strontium and barium.
 11. The process ofclaim 1 where the second metal cation is an alkali metal cation.
 12. Thecatalytic composite of claim 1 where the second metal is potassium. 13.The process of claim 1 where the third metal is palladium, platinum,nickel, and combinations thereof.